Influence of magnetic field on the transport properties of ferromganet/ferromagnet/s-wave superconductor junctions formed on the surface of a three-dimension topological insulator

Abstract

We study the influence of magnetic field on the transport properties of ferromagnetic metal (FM)/ferromagnetic insulator (FI)/s-wave superconductor (s-wave SC) junctions and FM/FM/s-wave SC junctions formed on the surfaces of three dimensional topological insulators (3DTI), where the magnetic field is applied perpendicular to the s-wave SC surfaces. For a broad range of the magnetic field strength, the conductance is investigated. Unlike the preceding studies, we apply the magnetic field to the superconductor surfaces of the junctions instead of the magnetization induced by the ferromagnets adjacent to their surfaces. We determine the dependence of conductance on the magnetic field for the cases of parallel and antiparallel magnetizations and reveal that the magnetoresistance sensitively depends on the magnitude of the magnetic field for the biases below the renormalized gap. The results obtained in this work will find applications in superconductor spintronics.